* Astronomy

Blobrana · L

RE: P Cygni

Blobrana · L

Google earth file: P Cygni.kmz (2kb, kmz)

Blobrana · L

P Cygni (34 Cyg) is a variable star in the constellation Cygnus. It is a hypergiant luminous blue variable (LBV) star of spectral type B1Ia+ that is one of the most luminous stars in the Milky Way galaxy. The star is located about 5000 to 6000 light years from Earth. It was unknown until the end of the 16th century, when it suddenly brightened to 3rd magnitude. It was first observed on 8 August 1600 by Willem Janszoon Blaeu, a Dutch astronomer, mathematician and globe-maker. After six years the star faded slowly, dropping below naked-eye visibility in 1626.
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Blobrana · L

Title: An Indication for the Binarity of P Cygni from Its Seventeenth Century Eruption
Authors: Amit Kashi

I show that the 17th century eruption of the massive luminous blue variable (LBV) star P Cygni can be explained by mass transfer to a B-type binary companion in an eccentric orbit, under the assumption that the luminosity peaks occurred at periastron passages. The mass was accreted by the companion and liberated gravitational energy, part of which went to an increase in luminosity. I find that mass transfer of ~0.1 solar masses to a B-type binary companion of ~3-6 solar masses can account for the energy of the eruption, and for the decreasing time interval between the observed peaks in the visual light curve of the eruption. Such a companion is predicted to have an orbital period of ~7 years, and its Doppler shift should be possible to detect with high spectral resolution observations. Explaining the eruption of P Cygni by mass transfer further supports the idea that all major LBV eruptions are triggered by interaction of an unstable LBV with a stellar companion.

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Blobrana · L

Title: A deep mosaic of (O III) 5007 A CCD images of the environment of the LBV star P Cygni
Authors: P. Boumis (1), J. Meaburn (1,2), M. P. Redman (3), F. Mavromatakis (4) ((1) Institute of Astronomy & Astrophysics, National Observatory of Athens, Greece, (2) Jodrell Bank Observatory, University of Manchester, UK, (3) Department of Physics, National University of Ireland Galway, Ireland, (4) Technological Education Institute of Crete, General Department of Applied Science, Heraklion, Crete, Greece)

A mosaic of six, deep, CCD images in the light of the (O III) 5007 A nebular emission line has been obtained with the 1.3-m Skinakas (Crete) telescope of the filamentary nebulosity surrounding P Cygni. The (O III) 5007 A line discriminates against confusing galactic H II regions along the same sight-lines and the new mosaic did not include the 4.8 mag. central star; a source of artefacts in the previous lower angular resolution observations. New giant `lobes' and `shells' are found to be clustered around P Cygni which must be the relics of historic eruptions between 2400 and up to ~10^5 yr ago.

A mosaic of six (O iii)5007 °A images of the field around P Cygni is shown.
These have been continuum subtracted and only residuals from this process, for the brighter stars, are apparent. The central panel is filled by part of the original (N ii)6584 °A image from O’Connor et al. (1998) where an occulting mask suppressed the image of the 4.8 mag star P Cygni. This is presented to show the extent of the outer shell, OS and the connections to the various GLs.

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